The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 24, 1990
Filed:
Apr. 13, 1988
Adrian B Early, Buda, TX (US);
Larry L Harris, Austin, TX (US);
Michael J Callahan, Jr, Austin, TX (US);
Crystal Semiconductor, Austin, TX (US);
Abstract
A self-calibrated analog-to-digital converter with a corrected output includes an analog modulator (18) for receiving an analog input voltage and outputting a pulse train having a value proportional to the analog input voltage. The pulse train is filtered by a digital filter (20) which has the output thereof input to a calibration module (24). The calibration module (24) is controlled by a calibration control circuit (28) and is operable to correct the output to account for offset and gain errors. Prestored calibration parameters in a register (30) are utilized for this compensation. In a self-calibration mode, the control circuit (28) is operable to control a calibration multiplexer (12) to select a zero-scale input voltage on a terminal (16) and a full-scale reference voltage on a terminal (14) for input to the modulator (18). The multiplexer (12) is controlled to selcet the zero-scale reference to calculate an offset value for storage in the register (30) and then subsequently select the full-scale reference to calculate a scale factor for storage in the register (30 ). The self-calibration mode utilizes a settling counter (36) to insure that the output of the filter (20) has settled prior to making any calculations.